This application is based on application No. 11-150823 filed in Japan on May 31 1999, the content of which is incorporated hereinto by reference.
This invention relates to a high power source used primarily to power a drive motor for automobiles such as hybrid and electric automobiles.
A high current power source used to power an automobile drive motor achieves high output voltage by series connection of a multiplicity of battery cells. This is for the purpose of increasing drive motor output. An extremely high current flows in the power source used for this type of application. For example, in a hybrid automobile, an extremely high current flows in a power source when starting and accelerating because the automobile is accelerated by battery output. It is important for the high current power source to be charged discharged depending on battery condition and, in particular, on battery temperature measured by sensors. This is because an abnormal battery temperature rise results in a drastic reduction of battery efficiency.
To measure battery temperature, batteries mutually connected in series are provided on their surfaces with temperature sensors such as PTC devices which change electrical resistance with battery temperature. Ideally, temperature sensors detect the temperature of all batteries. If any battery temperature has not been detected, and the battery temperature has risen abnormally high, battery performance degradation may occur. In a power source used for automobiles, a multiplicity of batteries are connected in series to increase drive motor output. For this reason, if temperature sensor leads provided with all batteries are individually extracted, the number of the sensor leads becomes extremely large and a circuit for managing temperature becomes complex. For example, when a power source in which two hundred rechargeable batteries are connected in series is designed to detect each battery temperature, the power source requires at least two hundred and one leads.
A power source in which temperature sensors provided on all batteries are mutually connected in series can detect that battery temperature has risen abnormally by two leads regardless of the number of series connections of the batteries. For example, when any battery temperature has risen higher than the set temperature of PTC devices used as temperature sensors, electric resistance of the PTC devices connected in series is markedly increased.
To realize this, a power source containing a multiplicity of batteries, as shown in the diagrammatic cross-section view of FIG. 1, has sensor leads 3014 connected to power module 301 temperature sensors 3013, and are mutually connected in series via sensor connecting plates 3025. In the power source shown in this figure, sensor connecting plates 3025 are fixed, in an insulated state, to end regions of a holder-case retaining a plurality of power modules 301, and power module 301 sensor leads 3014 located adjacent to both ends of the sensor connecting plates 3025 are connected to the sensor connecting plates 3025 via setscrews 3035.
As shown in FIG. 2, in the power source having the connecting structure for power modules 301 shown in FIG. 1, plastic end-plates 303 are fixed to ends of the holder-case retaining power modules 301, and metal sensor connecting plates 3025 are fixed to the end plates 303 to allow the sensor connecting plates 3025 to be disposed in an insulated state and in fixed positions. For example, a power source with this structure is cited In Japanese Non-examined Patent Publication HEI. 10-270094 (1998). As shown in the oblique view of FIG. 3, the power source necessitates connection of sensor connecting plates 3025 on the backsides of plastic end-plates 303.
In the power source with the structure described above, power module 301 sensor leads 3014 are connected to both ends of a sensor connecting plate 3025 fixed to an end-plate 303 via setscrews to mutually connect them in series. This type of power source, however, requires connection of sensor leads 3014 disposed on both ends of all power modules 301 to the sensor connecting plates 3025 via setscrews 3035. Accordingly, the power source requires screw-fastening of sensor leads 3014 to sensor connecting plates 3025 in twice as many places as the number of necessary power modules 301. A power source contains a considerably large number of power modules. For example, a power source having the end-plates shown in FIGS. 2 and 3 houses sixteen power modules and requires thirty-two screw-fastenings of sensor leads 3014 to the sensor connecting plates 3025. For this reason, this type of power source has the drawback that assembly work requires much time, and manufacturing cost becomes high. Further, trouble with connecting parts of sensor leads 3014 (such as contact failure) easily occurs, and this makes it difficult for a power source with a large number of connecting parts to improve reliability. If contact failure occurs in sensor leads 3014, the power source can not work normally because of the trouble. In case of a power source used for automobiles, high reliability is necessary. This is because any trouble with a power source results in stopping of the motor.
The present inventor developed the power source shown in FIGS. 4 and 5 to resolve these problems. In that power source, adjacent power module 401 sensor leads 4014 are connected on an end-plate 403. Furthermore, one of the power module 401 sensor leads 4014 is extended to the other sensor lead 4014 to directly connect with it on the end-plate 403. In addition, reference numbers 4013, 4035 and 4025 show a temperature sensor, a setscrew and a sensor connecting plate in these figures.
A power source with this structure can be easily assembled and can drastically reduce manufacturing cost due to reducing the number of sensor lead connecting parts by half. In addition, the power source has the characteristic that contact failure in the sensor lead connecting parts can be reduced to improve reliability.
This type of power source, however, has the drawback that if two connecting parts disposed at the ends of sensor leads slip out of end-plate connecting positions, it requires a remarkably large amount of time to set the sensor lead connecting parts in fixed positions of the end-plate. Unfortunately, it is extremely difficult to process the connecting positions disposed at the ends of sensor leads with high precision since the positions easily slip from the end-plate fixed positions. This is because a plurality of batteries are connected in series, the sensors are fixed on the surfaces of batteries, and sensor leads are connected to the sensors. There is some error in measurement in batteries, and the measurement error in batteries is greater than in plastic and metal manufactured goods. Further, the measurement error in power modules in which a plurality of batteries are connected becomes even greater due to accumulation of the battery measurement error. Still further, it is difficult to accurately fix the sensors in fixed positions disposed on the battery surfaces. These are accumulated and cause slippage of sensor leads from the fixed connecting positions. For this reason, a power source having the structure shown in FIGS. 4 and 5 can realize the characteristic that the number of sensor lead connecting places can be reduced, but makes it difficult to efficiently connect sensor leads in each fixed connecting position. Furthermore, this type of power source has the drawback that connecting work requires much time, and assembly cost becomes high due to a considerably large number of power module series connections and a large number of sensor lead connecting parts.
The present invention was developed to resolve these types of problems with prior art power sources. Thus, it is a primary object of the present invention to provide a power source in which a multiplicity of sensor leads can be assembled simply, easily and efficiently, and in which assembly cost is low even though there is some error in measurement in the sensor leads.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with the accompanying drawings.
The power source of the present invention includes a plurality of power modules with sensor leads projecting from their end regions. A holder-case for holding the power modules is disposed in a parallel fashion, and end-plates is provided with pass bars for connecting the power modules in series. Sensor leads of adjacent power modules housed within the holder-case are connected outside the end-plates.
Further, in the power source of the present invention, power module sensor leads are flexible lead wires, and the sensor leads of adjacent power modules housed in the holder-case are extended to the length allowing them to be connected outside the end-plates. The end parts of the extended sensor leads are directly connected via connecting implements outside the end-plates.
The power source with this structure has the characteristic that a multiplicity of sensor leads can be assembled easily and efficiently, and assembly cost is low. Further, the sensor leads can be connected easily and efficiently even if the connecting parts cannot accurately meet due to the sensor lead measurement error.